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2010
Conference Paper
Titel
Power semiconductor joining through sintering of Ag-nanoparticles: Analysis of suitability of different powders using DSC and TGA measurements
Alternative
Halbleiter verbunden durch Sintern von Silber-Nanaopartikeln: Analyse der Eignung verschiedener Puder mittels DSC und TGA Messungen
Abstract
Power electronic systems are needed in diverse areas such as electricity transmission or electrical drives in industrial applications. Due to losses inside the chips, cooling is necessary. Si-chips can theoretically tolerate up to 200°C; solder interconnects are not suitable for temperatures exceeding 125°C, though. Furthermore, many solders comprise lead, which has been banned by government initiatives such as the European RoHS. Therefore, other means of interconnection have to be found. One approach is a sintering technology that joins chips and substrates by sintering of a silver flake powder [1, 2]. Due to the application of an external pressure of 30 to 50 MPa, sintering takes place at temperatures below 300°C. However, these pressures can lead to cracking of the brittle silicon chips and ceramic substrates. The next step is to use silver nanoparticles instead of micron-scaled silver flakes [3, 4]. Their huge surface energy leads to improved sinterability. Due to this fact, the pressure needed could be brought down to less than 5 MPa. The particles are passivated using organic capping materials to avoid agglomeration. The work shown in this article investigates the influence of the passivating material on the sintering behaviour of silver nanoparticles and evaluates their suitability for die bonding at temperatures below 300°C. For this, differential scanning calorimetry measurements (DSC), thermogravimetric analyses (TGA) and combined gas chromatography/mass spectroscopy (GCMS) were run.